There is no category for SDDM. Currently it's confusing to know which category to choose.
SDDM is not a kde project. Report issues at https://github.com/sddm/sddm/issues
Understood. If eventually I report a bug about Breeze SDDM theme, I must choose Breeze > General?
Maybe creating a SDDM subcategory for Breeze would be great.